BEIJING — China’s Communist Party has cleared the way for President Xi Jinping to stay in power indefinitely, by announcing Sunday that it intends to abolish term limits on the presidency, a momentous break with decades-old rules meant to prevent the country from returning to the days when Mao was shown cultish obedience.

The surprise move, revealed in a dryly worded proposal to amend the Constitution, is the boldest yet by Mr. Xi as he seeks to strengthen the party’s control over a modernizing society and restore China to what he considers its rightful place as a global power — an agenda that his allies have suggested requires his personal leadership.

He has pressed China’s claims over the South China Sea, begun a global infrastructure plan called the Belt and Road initiative, drastically reorganized the military, bulked up domestic security and enforced ideological purity in schools and media — all parts of his vision of China as a prosperous, respected player on the world stage that stays faithful to its Communist and Confucian roots.

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Soon after China’s Communist Party announced a plan to end presidential term limits, its censors and propaganda machine kicked into high gear. Here’s how it unfolded.CreditCreditGreg Baker/Agence France-Presse — Getty Images

The timing of the announcement startled even experienced observers of Chinese politics: Mr. Xi completes his first term as president next month and could have waited until late in his second term to act. He also could have stepped down after his second term and run the country from behind the scenes, as some of his predecessors have.

The move alarmed advocates of political liberalization in China who saw it as part of a global trend of strongman leaders casting aside constitutional checks, like Vladimir V. Putin in Russia and Recep Tayyip Erdogan in Turkey.

The Constitution now limits Mr. Xi, who became president in 2013, to two terms in that office, amounting to 10 years. But the party leadership has proposed removing the line that says the president and vice president “shall serve no more than two consecutive terms,” Xinhua, the official news agency, reported on Sunday.

By moving so early in his tenure, Mr. Xi, 64, is in effect proclaiming that he intends to stay in office well past 2023, overturning rules of succession in Chinese politics that evolved as the party sought stability following the power struggles to replace first Mao, and then Deng Xiaoping.

“Xi Jinping will certainly continue,” said Zhang Ming, a retired historian at Renmin University in Beijing. “In China, he can do what he wants to do, and this is just sending a clearer signal of that.”

Mr. Xi already serves as the party’s general secretary and the military chief, positions with no term limits.

“This is the next step in the continuing breakdown of political norms that had held sway in China’s reform era,” said Carl Minzner, a professor of law at Fordham University in New York and author of a new book on Mr. Xi’s increasing authoritarianism.

“What are the risks of these shifts?” Professor Minzner said. “In the short term, all the traditional dangers that arise from the excessive centralization of power in the hands of one person. But in the long term, the real question is how far the breakdown in political norms could go.”

Jiang Zemin, the leader who succeeded Deng, was installed during the Tiananmen protests of 1989 and served two terms as president from 1993 to 2003. But he lingered in power until 2004 by retaining control of the committee that runs China’s military.

His successor, Hu Jintao, stepped down from all his positions after his two terms — an example that some experts had expected Mr. Xi to follow.

But as Mr. Xi’s first term comes to an end, few in China see much likelihood of his power being subdued anytime soon by rivals in the leadership elite.

“Xi is now unfettered. He owns the entire policy process,” Susan Shirk, the head of the 21st Century China Center at the University of California, San Diego, wrote in a forthcoming paper about politics under Mr. Xi. “And Chinese domestic and foreign policy is only as restrained or aggressive as he wants it to be. The risk of policy misjudgments is greater than it has been under any other leader since Mao died.”

During his first term, Mr. Xi pressed an aggressive campaign against corruption and dissent, a crackdown that has silenced potential rivals in the leadership. At the same time, many party elders, who once held intimidating influence, have died or are too old for political intrigue. Mr. Jiang is 91, and Mr. Hu, 75, has shown no appetite for taking on Mr. Xi.

On the Chinese internet, some people eluded the party’s censors and mocked Mr. Xi’s ambitions by sharing images like that of Winnie the Pooh — portly like Mr. Xi, and used by critics to represent him — hugging a huge jar of honey.

But many people in China have applauded his campaign against official corruption. And harsh security measures make mass protests against a central leader nearly impossible. So any major public backlash against Mr. Xi’s move appears unlikely.

“I don’t see any reasonable challenges for him,” Wu Qiang, a political analyst in Beijing who formerly taught at Tsinghua University, said of Mr. Xi. “He has removed any potential political competitors. So far, there is no organized political competition for him.”

The proposed constitutional changes were released in the name of the Central Committee, a council of hundreds of senior party officials, who will meet starting on Monday for three days.

Mr. Xi had already built expectations that he would stay in office past two terms, and some analysts said he must have decided to move while at peak political strength. Usually, authority begins to ebb from Chinese leaders as retirement nears.

“I can see where his thinking is that he’s riding high, he’s got the momentum, and took the initiative to ram this through,” said Jude Blanchette, an expert on Chinese politics in Beijing who works for the Conference Board, which provides research for companies. “Why risk diminished power three years from now if the economy tanks or there’s a conflagration with North Korea, and not have the ability to do it?”

In another victory for Mr. Xi, the draft amendments to the Constitution would add his trademark expression for his main ideas — “Xi Jinping Thought on Socialism with Chinese Characteristics for a New Era” — into the preamble of the Constitution, as well as adding a nod to the ideological contributions of his predecessor, Mr. Hu.

The proposed amendments would also authorize a new anticorruption commission that Mr. Xi has pushed. The commission would expand the reach of corruption investigations, which up to now have mostly been conducted by a Communist Party agency acting largely beyond the law.

The amendments are almost certain to be passed into law by the party-controlled legislature, the National People’s Congress, which holds its annual full session starting on March 5. The congress has never voted down a proposal from party leaders.

In what would be another break with tradition, Wang Qishan, a close ally of Mr. Xi in his campaign against corruption and disloyalty in the party, appears set to return to power as vice president. Mr. Wang, 69, stepped down from a party position last year because of his age.

The abolition of the term limit may also explain another recent move by Mr. Xi to send one of his closest advisers, Liu He, to Washington on Tuesday. While that trip had initially looked like an attempt to discuss the Trump administration’s tougher rhetoric on trade, it now seems likely to also be a mission to explain Mr. Xi’s plans to American leaders.

At the Communist Party national congress in October, Mr. Xi conspicuously broke with precedent by choosing not to name a pair of much younger officials to the Politburo’s ruling inner circle, the seven-member standing committee, to serve as his potential heirs. Instead, Mr. Xi chose men — no women — who were closer to his own age or older.

Mr. Xi’s strongman style has been compared to that of the Russian president. But even Mr. Putin did not try to erase his country’s constitutional limit on serving more than two consecutive terms as president when he approached that limit in 2008.

Instead, he arranged for a close adviser, Dmitri A. Medvedev, to serve as president for a single term while Mr. Putin held the post of prime minister. Mr. Putin then returned to the presidency in 2012, and is running this year for re-election.

With Mr. Xi’s hold on power now seems unquestioned for the foreseeable future, the biggest question will be how he chooses to wield it.

“Xi Jinping is susceptible to making big mistakes because there are now almost no checks or balances,” said Willy Lam, an adjunct professor at the Chinese University of Hong Kong who is the author of a 2015 biography of Mr. Xi. “Essentially, he has become emperor for life.”

Javier C. Hernández contributed reporting from Beijing and Jane Perlez from Hong Kong. Additional research by Adam Wu in Beijing.

A version of this article appears in print on , on Page A1 of the New York edition with the headline: China Moves to Allow Xi To Stay in Power for Years. Order Reprints | Today’s Paper | Subscribe